Based on our extremely encouraging experience to date, we propose to pursue proton beam therapy for the treatment of cancer. We will continued randomized clinical trials of proton vs. x-ray therapy for stage T3-4 carcinoma of the prostate and for carcinoma of the floor of mouth and base of tongue. We will continue our non-randomized trials of proton beam therapy of chordomas and chondrosarcomas of the base of skull and cervical spine and of choroidal melanomas. We will determine whether the excellent local results seen to date with these sites is maintained. We plan two-dose randomized trials in selected patients in both these categories. We are planning new clinical trials in the treatment of paraaortic lymph node disease; meningiomas; superior sulcus tumors; acoustic neuromas; large choroidal melanomas; and anal and rectal tumors. We will take advantage of the unusual dose distributions obtained with proton beams to get clinical data concerning the tolerance of sensitive organs to partial volume irradiation and will correlate any observed treatment complications with the dose delivered to the sites involved. We will continue improvements in our capability to plan and deliver proton beam treatments with the goal of making possible the wider clinical dissemination of this treatment modality. One such project is to investigate the possibility of a "no touch" technique for the treatment of choroidal melanomas. The primary objective of the study is to evaluate whether the improvement in dose distributions achievable with proton beam therapy can be used to deliver an increased dose to the tumor with no greater and potentially less morbidity, and whether such an increased dose will lead to improvements in local control of cancer. If this program continues to demonstrate the advantages of protons which have been experienced to date, it will provide an important therapeutic option for several cancers which pose great difficulties for conventional treatment techniques.